Method and arrangement for the photographically detecting the spatial form of an object

ABSTRACT

A method of detecting the 3D shape of an object by photogrammetry, in which a plurality of photogrammetric point markers and a plurality of connecting markers are provided on the surface of the object, each connecting marker connecting a subset of the plurality of point markers with each other, with at least two different types of point markers existing that differ from each other in their optical configuration, and some of the point markers provided along a connecting marker are formed in such a way that the sequence of their optical configurations results in a predetermined code that characterizes the respective connecting marker, a plurality of photogrammetric images of the object are taken from different views, an image processing of the images is performed, in which first the connecting markers mutually corresponding to each other in the images are associated with one another using their respective code, and then the point markers connected with each other by the respective connecting marker are associated with one another with the aid of the connecting marker association in the images, and using the point marker association, the 3D shape of the object is determined by means of a photogrammetric evaluation process. The invention further relates to an arrangement for carrying out the method.

FIELD OF THE INVENTION

The invention relates to a method and an arrangement for thephotogrammetric detection of the 3D shape of an object.

BACKGROUND OF THE INVENTION

In connection with the so-called “mass customization”, i.e. theproduction and sale of products individually adapted to the bodymeasurements of a customer, the detection of the three-dimensionalspatial shape of the body or of body parts is an important problem to besolved in engineering. When the three-dimensional spatial shape of abody part e.g. the torso/leg region of a customer, is known, individualarticles of clothing such as pants, shirts, etc. may be manufacturedwith a very good fit.

A number of body scanners have been developed which detect and digitizethe three-dimensional shape of the human body or of body partscontactlessly, using various optical methods, e.g. laser triangulation,stereo methods, moirémethods, etc., in which the data records describingthe digitization are then made available for the automated production ofindividually adapted products. As a rule, such body scanners operatewith technically very sophisticated and expensive processes which, inaddition, require optical calibration and can therefore be employed onlyby trained specialist staff.

The so-called passive methods of short-range photogrammetry areconsiderably more cost-effective since merely calibrated cameras ordigital cameras are required, rather than expensive projection units orprecisely calibrated mechanical structures.

For instance, the Patent EP 0 760 622, “Sensing Process and Arrangementfor the Three-Dimensional Shape in Space of Bodies or Body Parts”, theapplicant and inventor of which is Robert Massen, discloses a methodwhich allows an optical detection of the 3D coordinates of a body orbody part, involving very little technical expenditure. To this end, thebody is covered with an elastic envelope specially marked with preciselylocated point markers, and photographs of the body are taken from aplurality of camera positions that overlap but are otherwise takenfree-handed. By a photogrammetric evaluation of the corresponding pointmarkers in the individual overlapping image areas of the photographs, a3D data record of the body part may be established.

In order to allow a 3D reconstruction of the body part from the pointmarkers provided on the body part or on an envelope pulled over the bodypart based on two overlapping image recordings using methods ofphotogrammetry, the pixel coordinates of the so-called homologous pointmarkers, i.e. of the point markers mutually corresponding to each otherin the images need to be determined. This process is also referred to asregistration. Therefore, in an automatic registration, those pointmarkers which correspond to each other need to be found from twooverlapping image recordings using methods of two-dimensional imageprocessing. In previous known methods, this is achieved by the use ofindividually encoded point markers. The point markers used are circles,for example, that are surrounded by radial segments representing abinary code (in this connection see the left-hand part of FIG. 1). Here,the center of the encoded marker defines the location of thephotogrammetric point marker. The radial segments provide a uniquecharacterization for each point marker by a code of its own.

In the prior art methods, attempts are made with the aid of automaticimage processing to find such point markers in two images, to read theircode and to prepare a list of the corresponding point markers, i.e. thehomologous point markers. Once preparation of this list is complete, theknown methods of image orientation and bundle adjustment may be employedto establish a 3D data record containing the XYZ space coordinates ofall homologous point markers.

In the photogrammetric measurement of large structures such as vesselhulls, aircraft parts etc., the space required by such encoded pointmarkers is not relevant. However, a disadvantage of the prior artmethods for the photogrammetric determination of the 3D shape of anobject, which make use of individually encoded point markers that covera relatively large area consists in that these methods are not suitablefor the digitization of very small objects, which need to be coveredwith many point markers due to the required spatial point density. Whenusing encoded point markers as are illustrated in FIG. 1, for example,in such cases the space offered by the surface of the object is notsufficient for achieving the spatial point density necessary for a goodphotogrammetric measurement.

In German Patent Application Serial Number 100 25 922.7 entitled“Automatische photogrammetrische Digitalisierung von Körpern undObjekten” (“Automatic Photogrammetric Digitization of Bodies andObjects”), the applicant and inventor of which is Robert Massen, it isin addition proposed to provide area markers on the envelope describedin EP 0 760 622, which each comprise a plurality of point markers andform a background of the point markers, the surface area of the areamarkers having a particular color. The use of color image processingmethods allows an easy automatic determination of the area markers(regions) corresponding in the different photogrammetric images and thenof the corresponding point markers (so-called homologous pixels)therefrom. Once the list of the homologous pixels is available, the 3Ddata of the entire body part may be calculated using the methods ofimage orientation and bundle adjustment that are familiar to a person ofordinary skill in the art of photogrammetry.

A drawback of this method is that a relatively large number of differentcolors are needed for marking. Therefore, the color fidelity of thecameras employed must be sufficiently high and stable to be able toadequately differentiate between such multitude of different colors inan automatic recognition. Also, the standards applied to constancy andcolor fidelity of the illumination are higher than those in a markingtechnique, which would manage with only very few colors that aredistinctly different in the color space. A further disadvantage of thismethod resides in the relatively high geometric resolution required foroptically resolving the color edges and color corners used as markers.

Both requirements, high color fidelity and high geometric resolution,can not be satisfied by simple and very low-priced cameras such as forinstance by webcams based on CMOS image sensors or image sensorsincorporated in future mobile telephones and so-called personalorganizers (pocket computers). Thus, it is not possible for such verysimple and inexpensive image recording devices to be used for a simpledigitization of body parts as described above.

Therefore, a technical and economic interest exists in providing amethod and an arrangement for the photogrammetric detection of the 3Dshape of an object, featuring an improved marking technique that allowsa low-cost and simple measurement even of small objects.

Furthermore, there exists an interest in a method and an arrangement forthe photogrammetric detection of the 3D shape of an object that—withregard to the marking—manage with only few different colors and onlyrelatively rough structures, in order to enable an automaticdetermination of homologous pixels from a plurality of overlapping imagerecordings using inexpensive, low color fidelity and low resolutioncameras and imaging devices and with an illumination that may be of lowdefinition in respect of the color. This would permit to employ themethod even when using low-priced webcams (web cameras) or digitalcameras, for example, that are commonly used today and are rather poorlyspecified as regards color fidelity and resolution.

SUMMARY OF THE INVENTION

The interest as set forth above in this field of engineering is met inaccordance with the invention by a method of detecting the 3D shape ofan object by photogrammetry, in which

a plurality of photogrammetric point markers and a plurality ofconnecting markers are provided on the surface of the object, eachconnecting marker connecting a subset of the plurality of point markerswith each other, with at least two different types of point markersexisting that differ from each other in their optical configuration, and

some of the point markers provided along a connecting marker are formedin such a way that the sequence of their optical configurations resultsin a predetermined code that characterizes the respective connectingmarker,

a plurality of photogrammetric images of the object are taken fromdifferent views,

an image processing of the images is performed, in which first theconnecting markers mutually corresponding to each other in the imagesare associated with one another using their respective code, and thenthe point markers connected with each other by the respective connectingmarker are associated with one another with the aid of the connectingmarker association in the images, and

using the point marker association, the 3D shape of the object isdetermined by means of a photogrammetric evaluation process.

The interest described above is further satisfied by an arrangement fordetecting the 3D shape of an object by photogrammetry, which comprisesan imaging system for obtaining photogrammetric images of differentviews of the object and a system for processing and evaluating theimages and for determining the 3D shape of the object and ischaracterized in that the arrangement further includes a plurality ofphotogrammetric point markers and a plurality of connecting markers onthe surface of the object, each connecting marker connecting a subset ofthe plurality of point markers with each other, with at least twodifferent types of point markers existing that differ from each other intheir optical configuration, and some of the point markers providedalong a connecting marker being formed in such a way that the sequenceof their optical configurations results in a predetermined code thatcharacterizes the respective connecting marker.

Because of the fact that according to the invention it is not the pointmarkers themselves that are encoded individually, but a characteristicsequence of point markers of different types results in a code, an easyautomatic photogrammetric detection of even very small objects thatrequire a high point marker density is made possible.

Advantageous further developments of the invention are characterized inthe dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention will be apparent fromthe following description of an embodiment with reference to thedrawings, in which:

FIG. 1 shows two different encoded point markers according to the priorart;

FIG. 2 is a side view of a knee to be digitized using the methodaccording to the invention and provided with an envelope, and of acamera in two different imaging positions;

FIG. 3 is a top view of the knee illustrated in FIG. 2, with arepresentation of the imaging positions of a camera radially distributedabout the knee;

FIG. 4 shows a knee envelope photogrammetrically marked in accordancewith a first embodiment of the invention;

FIG. 5 a shows the knee envelope illustrated in FIG. 4, in a firstimaging position:

FIG. 5 b shows the knee envelope illustrated in FIG. 4, in a secondimaging position;

FIG. 6 shows the form of photogrammetric marking used in a furtherembodiment of the invention;

FIG. 7 shows the form of photogrammetric marking used in a furtherembodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention will now be described by way of example, which is not tobe construed in a limiting sense, with reference to the photogrammetricdetection of the 3D shape of a knee region for the purpose of anautomatic production of a knee orthesis.

Assuming, for example, that the knee is covered with an elastic envelopehaving photogrammetric markers applied thereto. The photogrammetricmarkers may however also be applied by a variety of other methods. Forinstance, the markers may be provided on the object by applying paintsuch as make-up directly onto the object, by projection with the aid ofa projection system, or by sticking self-adhesive films onto the objectwhich have the markers applied thereto.

The knee 1 illustrated in FIG. 2, shown with the adjoining thigh andlower leg regions, which is to be digitized by way of example, roughlyhas a cylindrical basic shape. The required overlapping photographicimages are expediently taken in this case in the form of views from allaround the cylindrical body part; to ensure sufficient overlap, about 8to 10 images distributed over the periphery are needed.

FIG. 3 shows how a patient's knee region 1, clad in a marked elasticenvelope (2 in FIG. 2), is imaged from eight radial positions, A1 to A8,using a camera. FIG. 2 shows a side view of the knee in which the cameracan be seen only in the positions A3 and A7. For the photogrammetricevaluation it is merely important in this connection that the angularoverlap area of the individual images includes a sufficient number ofhomologous, i.e. mutually corresponding, photogrammetric point markers.For obtaining such sequence of images from all around, the camera mayfor instance be manually guided around the leg at the same level.

FIG. 4 shows the knee region 1 with the elastic envelope 2, which hasdifferent photogrammetric markings according to the invention applied toit.

In its lower area 3 the envelope 2 is dyed in a first color that forms adistinct contrast to the spatial background R likewise acquired by thecameras and is represented by a light shade of gray in FIG. 4. The colorselected will suitably be a color that is rather rare in everydaysurroundings, such as pink. Grid lines are applied on the light shade ofgray, the points of intersection of the vertical and horizontal gridlines 4 and 5 forming accurately located photogrammetric point markerswhich will hereinafter also be referred to as point markers notcontributing to encoding because they can not be distinguished from oneanother and do not contain a code and are unable to serve for encoding.

In its upper area 6 the envelope 2 is dyed in a second color that formsa sharp contrast to the spatial background R and a sharp contrast to thefirst color of the lower area 3 (e.g., light green). The second color isrepresented by a dark shade of gray in FIG. 4. The vertical lines 4 ofthe grid structure of the lower area 3 also extend into the upper area.

In the upper area 6 the point markers are formed in that a relativelyshort horizontal line runs toward a vertical line 4 to end at thevertical line, the meeting point defining the precisely located pointmarker. As can be seen in FIG. 4, there are two different types of pointmarkers here, namely those in which the relatively short horizontal lineruns toward the vertical line of the grid structure from the left andthose in which the relatively short horizontal line runs toward thevertical line of the grid structure from the right.

Along each vertical line 4 of the grid structure, in the following alsoreferred to as connecting marker since it connects various point markerswith one another, there are arranged in the upper colored area 6 fourpoint markers whose sequence, i.e. the sequence of the arrangement oftheir horizontal lines (e.g., running toward the vertical line from theleft, from the right, from the left, from the left), uniquely identifiesthe respective connecting marker. The connecting markers connect pointmarkers located in the upper area 6 with the point markers located inthe lower area 3.

With the aid of a simple color classification, carried out pixel bypixel, the “KNEE” region in each image recorded can already beautomatically segmented from the background based on the first color,and the code region 6 within the “KNEE” region can be localized by thesecond color. A person of ordinary skill in the art of image processingknows how to robustly carry out such automatic color segmentations (cf.,e.g., Robert Massen: “Form und Farbe: Farbbildverarbeitung für dieindustrielle Überwachung in Echtzeit” (“Shape and Color: Color ImageProcessing for Real-Time Industrial Monitoring”), in: MaschinellesSehen, Europa-Fachpresse publishing house, 1990, ISBN 3-87207-004-5).

The markers required for photogrammetric evaluation point and connectingmarkers) are represented by black high-contrast lines, the size of thewidth of these lines being selected such that they can still be imagedeven by inexpensive cameras usually featuring only low resolution. Thepoints of intersection of the lines and, in the code area 6, the pointsof encounter, respectively, represent the actual photogrammetric pointmarkers. The position of the point markers may be determined with highaccuracy with the aid of interpolation methods (sub-pixelinterpolation), so that in spite of a poor geometric camera resolutionprecisely located point marker coordinates may be measured. Using suchsub-pixel interpolations known to a person of ordinary skill in the artof image processing, it is possible in this way to determine the XYposition of the center of mass of a grid crossing with a precision whichis about 5 to 10 times higher man the size of the imaging pixel.

The connecting lines between the points of intersection serve as“optical tracks”, along which the automatic image evaluation may proceedsystematically from one point of intersection to the next. In this way,they establish the neighborhood relations between the markers thatcontribute to encoding or the non-encoded markers both in the verticaland horizontal directions.

In order to allow a 3D reconstruction of the markers provided andsecured on the knee envelope based on two overlapping image recordingsusing the methods of photogrammetry, the pixel coordinates of thehomologous point markers need to be determined, something which is alsoreferred to as registration. In an automatic registration, those markerswhich correspond to each other need to be found from two overlappingimage recordings using methods of 2-dimensional image processing. In theprior art his is achieved by the use of individually encoded, relativelylarge-surface point markers as are illustrated in FIG. 1, for example.Then, with the aid of automatic image processing according to the priorart, point markers are found in two images, their code is read, and thena list of the corresponding markers, i.e. the homologous point markers,is prepared. When the preparation of this list is complete, a 3D datarecord containing the XYZ space coordinates of all homologous pointmarkers may be established using the known methods of image orientationand bundle adjustment.

In accordance with the invention, on the other hand, a characteristicsequence of simple and very small point markers of different types isused to characterize connecting markers (e.g., lines that connect thepoint markers with each other) on each of which a specific subset of thepoint markers and especially the point markers that do not contribute toencoding is arranged in succession. The unique association of the pointmarkers that do not contribute to encoding may be obtained here from theneighborhood relations between the encoded markers.

In addition, in accordance with the invention a space-saving encoding isused which is structured in such a way that the individual codepositions of the encoded marker may each be used as a photogrammetricpoint marker. In so doing, a four-digit code, for instance, is formednot only by one point marker, but from four point markers. In the usualmethod involving point markers encoded with radial segments (seeleft-hand side in FIG. 1) there is only one single point marker per code(i.e. for all of the code elements together). The method according tothe invention therefore multiplies the number of available point markersby the factor N, where N denotes the number of code positions (bitpositions in a binary code). Thus, a body part may be digitizedconsiderably more densely because it may be covered with encoded pointmarkers at a higher density.

FIGS. 5 a and 5 b show two images of the knee provided with theenvelope, taken from the different imaging positions, A5 and A4 (seeFIG. 3 in this respect). On the knee to be digitized, which is a more orless cylindrical body and for which the automatic association ofcorresponding pixels is to be determined from overlapping peripheralimages, the vertical grid lines (the lines oriented along thelongitudinal axis of the leg) Li are characterized in the code region 6,identified by the first color, by a binary code having the following twocode elements:

-   -   horizontal branching from the grid line to the left=logical        ZERO=O    -   horizontal branching from the grid line to the right=logical        ONE=L.

The image A5 in FIG. 5 a shows a four-digit binary code that uniquelyencodes each vertical line (connecting marker 4):

Line L 4=(OLOO)

Line L 0=(OOOO)

Line L 5=(OLOL)

Line L 10=(LOLO)

Line L 6=(OLLO)

The first code bit is represented, for instance, by the first gridbranching tat is encountered starting from the top. Owing to the clearlydefined color transition between the code region 6, the surface area ofwhich is dyed with the first color, and the remaining, lower knee region3, the surface area of which is dyed with the second color, the point ofencounter for decoding this code can be automatically found by methodsof color and half-tone image processing, even when the camera is rotatedor tilted between taking the images or is otherwise brought into anunknown imaging position.

FIG. 5 b shows the image A4 taken of the knee covered with the envelope,which was obtained from an imaging direction radially offset through 45degrees with respect to the image A5.

By an automatic reading of the code of the connecting marker (i.e., thevertical lines 4), the connecting markers mutually corresponding to eachother in the two images, A5 and A4, i.e., the homologous vertical lines4, can be immediately determined.

In the photogrammetric evaluation, now first of all an image processingof the images is performed, in which first the connecting markers 4mutually corresponding to each other in the images are associated withone another using their respective code, and then the point markersconnected with each other by the respective connecting marker areassociated with one another with the aid of the connecting markerassociation in the images, the 3D shape of the object being determinedby means of a photogrammetric evaluation method using the point markerassociation.

In this embodiment of the invention, it is of particular advantage thatthe “branching” code position may serve at the same time as aphotogrammetric point marker. The center of mass of a branching to theleft or to the right may be determined in the image evaluation just asprecisely as the center of mass of a continuous grid cross. Thus, incontrast to the known methods, this encoding is extremely space-saving.

A particular advantage of the invention consists in that each codeposition represents a point marker. Thus, such a code occupies little ofthe space required for the digitization because it is spread over aplurality of compact point markers.

Of course, this code need not be restricted to a binary code. FIG. 6,for instance, shows an encoding of the connecting markers (verticallines) using a ternary code which consists of the following elements,

-   -   horizontal branching to the left=A    -   horizontal branching to the right=B    -   branching to the left and to the right=C

With the aid of merely 3 different types of junctions (=code positions)it is already possible to uniquely encode 3*3=9 connecting markers(lines) so that such a code again takes up considerably less space thanthe binary code.

Under some circumstances it may be advantageous to have more codesavailable than are required for the unique identification of allconnecting markers, since additional codes may be used for codeprotection, error recognition and error correction. The use andinterpretation of redundant codes occurring herein for an automaticerror correction and error recognition of errors occurring in codereading are known to those of ordinary skill in the art of encoding.

It is apparent that the principle in accordance with the invention maybe employed in a multitude of different point markers, the point markersnot necessarily needing to consist of crosses or lines that encountereach other. All that is required is the provision of at least twodifferent types of point markers, the exact shape of the point markersbeing irrelevant; conforming to their function as point markers, theyonly need to be suitable to specify the location of a point on theobject.

Accordingly, with reference to FIG. 7, an embodiment of the invention isillustrated in which black points having different diameters areemployed as point markers, with a point having a small diameter (on theleft in FIG. 7) marking a logical zero and a point with a large diameter(in the center of FIG. 7) marking a logical one of the code.

In this way, the code “O L L L” is produced, for example, by placing onesmall and three large black circles one behind the other, see on theright in FIG. 7.

It is, of course, not absolutely required to use vertical straight linesas connecting markers connecting the point markers with one another. Forinstance, horizontal lines or curved lines may be used just as well.What is important is that the connecting markers produce a connectionbetween the point markers that are to be associated with the connectingmarkers. It is therefore further conceivable for the connecting markersthemselves to consist of points.

Thus, in accordance with the invention, three objects are achieved bythis marking according to the invention: a large-surface area encodingof a structure (heavy grid lines in the example described) is madepossible where the encoding is able to be acquired even by a poorresolution camera; such encoding may be utilized at the same time as amultitude of precisely positioned photogrammetric point markers; and anautomatic determination of homologous point markers may be carried outwith the aid of the determination of homologous connecting markers.

In other embodiments of the invention, the areas provided fordistinguishing between point markers that contribute to encoding andpoint markers that do not contribute to encoding may, of course, be madeto contrast with each other by the most varied of opticalconfigurations. Such optical configuration need not necessarily consistin a different color, but may also consist in a characteristic halftone, a characteristic texture, i.e. a characteristic pattern or acharacteristic structure, a characteristic gloss, a surface coatingapplied to the surface and having a characteristic degree ofpolarization, characteristic fluorescence properties, certain spectralsignatures, a specific local gloss, a specific local temperature, or acharacteristic combination of the above-listed optical configurationfeatures.

The high-contrast structures applied for the purpose of photogrammetricmarking may further distinguish themselves by reflection characteristicsin regard to a spectral range outside the visible range. For instance,they may contrast with the background only in the near infrared range,in the ultraviolet range or in some other range of wavelengths notvisible to the human eye. In this way, elastic envelopes may be producedhaving, e.g. an visible marking or a marking covered by a visiblecoloration intended for the human eye. They may be in the form ofswimsuits, for example, which on the one hand may be designed with an“aesthetic” pattern that is visible to the human eye and, in addition,configured with an invisible surface marking adapted to be detected byphotogrammetry and consisting of point and connecting markers.

1. A method of detecting the 3D shape of an object by photogrammetry,comprising the steps of: providing a plurality of photogrammetric pointmarkers and a plurality of connecting markers on the surface of theobject, each connecting marker connecting a subset of the plurality ofpoint markers with each other, with at least two different types ofpoint markers existing that differ from each other in their opticalconfiguration; some of the point markers provided along a connectingmarker being formed in such a way that the sequence of their opticalconfigurations results in a predetermined code that characterizes therespective connecting marker; taking a plurality of photogrammetricimages of the object from different views; performing an imageprocessing of the images, in which first the connecting markers mutuallycorresponding to each other in the images are associated with oneanother using their respective code, and then the point markersconnected with each other by the respective connecting marker areassociated with one another with the aid of the connecting markerassociation in the images; and using the point marker association,determining the 3D shape of the object by means of a photogrammetricevaluation process.
 2. The method as claimed in claim 1, wherein theconnecting markers consist of lines.
 3. The method as claimed in claim2, wherein the lines are straight.
 4. The method as claimed in claim 2,wherein the lines are curved.
 5. The method as claimed in any of thepreceding claims 2 to 4, wherein the point markers are each defined bytwo lines meeting each other, one of which is part of a connectingmarker that connect a subset of the point markers with one another. 6.The method as claimed in claim 5, wherein the different opticalconfiguration of the point markers consists in that some point markersrun from the one side of the line forming a connecting marker towardsuch line to end thereat, and some other point markers run from theother side of the line forming a connecting marker toward such line toend thereat, the sequence of point markers running toward the line fromthe one side or from the other side resulting in the code characterizingthe connecting marker.
 7. The method as claimed in claim 5, wherein thedifferent optical configuration of the point markers consists in thatsome point markers run from one side toward a line forming a connectingmarker to end at the line, and some point markers cross the line forminga connecting marker, the sequence of point markers running toward theline from one side and crossing point markers resulting in the codecharacterizing the connecting marker.
 8. The method as claimed in any ofclaims 1 to 4, wherein the point markers are formed by circles.
 9. Themethod as claimed in claim 8, wherein the different opticalconfiguration of the point markers consists in that the points havedifferent diameters.
 10. The method as claimed in claim 1, wherein thepoint markers that form a code are backed by an area having a first typeof optical configuration, and the remaining point markers that do notform a code are backed by an area having a second type of configurationthat differs from the first type.
 11. The method as claimed in claim 10,wherein the different optical configuration of the areas consists inthat the areas have different colors.
 12. The method as claimed in claim1, wherein the point and connecting markers are provided on the objectby pulling an elastic envelope having the markers applied thereto overthe object.
 13. The method as claimed claim 1, wherein the point andconnecting markers are provided on the object by applying the markersonto the object using paint.
 14. The method as claimed in claim 1,wherein the point and connecting markers are provided on the object byprojecting the markers onto the object.
 15. The method as claimed inclaim 1, wherein the point and connecting markers are provided on theobject by sticking self-adhesive films having the markers appliedthereto onto the surface of the object.
 16. The method as claimed inclaim 1, wherein the object is a body part of a human being.
 17. Asystem for detecting the 3D shape of an object by photogrammetry,comprising an imaging system for obtaining photogrammetric images ofdifferent views of the object and a system for processing and evaluatingthe images and for determining the 3D shape of the object, wherein thesystem for detecting the 3D shape of an object by photogrammetry furtherincludes a plurality of photogrammetric point markers and a plurality ofconnecting markers on the surface of the object, each connecting markerconnecting a subset of the plurality of point markers with each other,with at least two different types of point markers existing that differfrom each other in their optical configuration, and some of the pointmarkers provided along a connecting marker being formed in such a waythat the sequence of their optical configurations results in apredetermined code that characterizes the respective connecting marker.18. The system for detecting as claimed in claim 17, further includingan elastic envelope which has the point and connecting markers appliedthereto and is designed such that it can be pulled over the object andadapts to the shape of the object.
 19. The system for detecting asclaimed in claim 17, further including one or more self-adhesive filmshaving the point and connecting markers applied thereto and designedsuch that when stuck on the surface of the object, they are intight-fitting contact with the object.
 20. The system for detecting asclaimed in claim 17, further comprising a projection system designed tobe used for projecting the point and connecting markers onto die object.21. The system for detecting as claimed in claim 17, wherein the objectis a body part of a human being.